| 摘要 |
Telecine apparatus preferably of the line array type has the line scan rate controlled in response to a tachometer sensing the instantaneous film speed to overcome problems caused by film speed variations. The output signal is compensated in inverse relation to the scan period to compensate for consequent variations in the integration time for the array. For very slow film speeds the actual scan rate is increased from the required scan rate by a factor of a power of two and unwanted scans (dummy scans) are ignored. For very fast film speeds the actual scan rate is decreased from the theoretically required scan rate by a factor m, likewise a power of two, and a full picture formed from lines from the latest m/2 fields, or by repeating or interpolating lines in the latest field only. To find a shot change at low film speeds the output picture has two parts, the junction between them being defined by a particular line scan, and the two parts being derived from two adjacent film frames. When the film is stopped, one part of the picture is the normal interlaced output and another part formed from a line direct from the linear array to enable proper functioning of the array to be confirmed. |
